In recent years, various methods have been studied to improve luminance of AlGaInP-series light-emitting diodes (LEDs). With great breakthroughs in this area, the application of AlGaInP-series light-emitting diodes extends widely to display system, lighting system, automatic system, etc. For example, according to Chinese patent 201210341574.6, at least two Bragg reflector layers with different corresponding reflecting wavelength are provided to expand bandwidth of the reflection wavelength of LED and to improve internal quantum efficiency.